Method of conductively interconnecting electronic components, battery powerable apparatus, radio frequency communication device, and electric circuit

ABSTRACT

A curable adhesive composition is provided which comprises an epoxy terminated silane. A thin profile battery and a substrate to which the thin profile battery is to be conductively connected are also provided. The curable adhesive composition is interposed between the thin profile battery and the substrate. It is cured into an electrically conductive bond electrically interconnecting the battery and the substrate. In another aspect, the invention includes a method of conductively interconnecting electronic components using a curable adhesive composition which comprises an epoxy terminated silane. The invention in another aspect includes interposing a curable epoxy composition between first and second electrically conductive components to be electrically interconnected. At least one of the components comprises a metal surface with which the curable epoxy is to electrically connect. The epoxy is cured into an electrically conductive bond electrically interconnecting the first and second components. The epoxy has an effective metal surface wetting concentration of silane to form a cured electrical interconnection having a resistance through said metal surface of less than or equal to about 0.3 ohm-cm 2 . In another aspect, a battery powerable apparatus includes a conductive adhesive mass comprising an epoxy terminated silane between a battery and substrate. A radio frequency communication device is one example. In another aspect, the invention includes an electric circuit comprising first and second electric components electrically connected with one another through a conductive adhesive mass comprising an epoxy terminated silane.

RELATED PATENT DATA

This patent resulted from a divisional application of U.S. patentapplication Ser. No. 09/022,812, filed Feb. 12, 1998 now U.S. Pat. No.6,030,423, entitled “Thin Profile Battery Bonding Method and Method ofConductively Interconnecting Electronic Components”, naming Rickie C.Lake as inventor, and which is now U.S. Pat. No. 6,030,423, which issuedFeb. 29, 2000, the disclosure of which is incorporated by reference.

TECHNICAL FIELD

This invention relates to thin profile battery bonding methods, tomethods of conductively interconnecting electronic components, tobattery powerable apparatus, to radio frequency communication devices,and to electric circuits.

BACKGROUND OF THE INVENTION

Thin profile batteries comprise batteries that have thickness dimensionswhich are less than a maximum linear dimension of its anode or cathode.One type of thin profile battery is a button type battery. Suchbatteries, because of their compact size, permit electronic devices tobe built which are very small or compact.

One mechanism by which thin profile batteries are electrically connectedwith other circuits or components is with electrically conductiveadhesive, such as epoxy. Yet in some applications, a suitably conductivebond or interconnection is not created in spite of the highly conductivenature of the conductive epoxy, the outer battery surface, and thesubstrate surface to which the battery is being connected. Thisinvention arose out of concerns associated with providing improvedconductive adhesive interconnections between thin profile batteries andconductive nodes formed on substrate surfaces. The invention has otherapplicability as will be appreciated by the artisan, with the inventiononly being limited by the accompanying claims appropriately interpretedin accordance with the Doctrine of Equivalents.

SUMMARY OF THE INVENTION

The invention in one aspect includes a thin profile battery bondingmethod. In one implementation, a curable adhesive composition isprovided which comprises an epoxy terminated silane. A thin profilebattery and a substrate to which the thin profile battery is to beconductively connected are also provided, The curable adhesivecomposition is interposed between the thin profile battery and thesubstrate. It is cured into an electrically conductive bond electricallyinterconnecting the battery and the substrate.

The invention in another aspect includes a method of conductivelyinterconnecting electronic components. In one implementation, a curableadhesive composition comprising an epoxy terminated silane is provided.First and second electronic components to be conductively connected withone another are provided. The curable adhesive composition is interposedbetween the first and second electronic components. The adhesive iscured into an electrically conductive bond electrically interconnectingthe first and second components.

The invention in still another aspect includes interposing a curableepoxy composition between first and second electrically conductivecomponents to be electrically interconnected. At least one of thecomponents comprises a metal surface with which the curable epoxy is toelectrically connect. The epoxy is cured into an electrically conductivebond electrically interconnecting the first and second components. Theepoxy has an effective metal surface wetting concentration of silane toform a cured electrical interconnection having a contact resistancethrough said metal surface of less than or equal to about 0.3 ohm-cm².

The invention in a further aspect includes a battery powerableapparatus. In one implementation, such includes a substrate having asurface comprising at least one node location. A thin profile battery ismounted over the substrate and node location. A conductive adhesive masselectrically interconnects the thin profile battery with the nodelocation, with the conductive adhesive mass comprising an epoxyterminated silane.

The invention in still a further aspect includes a radio frequencycommunication device. In one implementation, such includes a substratehaving conductive paths including an antenna. At least one integratedcircuit chip is mounted to the substrate and in electrical connectionwith a first portion of the substrate conductive paths. A thin profilebattery is conductively bonded with a second portion of the substrateconductive paths by a conductive adhesive mass, with the conductiveadhesive mass comprising an epoxy terminated silane.

The invention in still another aspect includes an electric circuitcomprising first and second electric components electrically connectedwith one another through a conductive adhesive mass comprising an epoxyterminated silane.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a side elevational, partial cross sectional, view of a thinprofile battery.

FIG. 2 is a side elevational view of a substrate.

FIG. 3 is a side elevational view of a battery powerable apparatus.

FIG. 4 is a diagrammatic plan view of a radio frequency communicationdevice.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

Referring to FIG. 1, a single thin-profile battery is indicatedgenerally with reference numeral 10. In the context of this document,“thin-profile battery” is intended to define any battery having athickness dimension which is less than a maximum linear dimension of itsanode or cathode. The preferred and illustrated battery 10 comprises acircular button-type battery. Such comprises a lid terminal housingmember 14 and a can terminal housing member 12. Can 12 is crimped aboutlid 14, having an insulative sealing gasket 16 interposed therebetween.In the illustrated example, gasket 16 projects outwardly slightlyrelative to the crimp as shown.

FIG. 2 illustrates a substrate 22 to which thin-profile battery 10 is tobe conductively connected. Substrate 22 includes an outer surface 23having one node location 24 and another node location 25 to whichbattery electrical connection is desired. Substrate 22, for example, cancomprise a flexible circuit substrate, wherein nodes 24 and 25 compriseprinted thick film ink formed on surface 23.

Referring to FIG. 3, a curable adhesive composition or mass 26comprising an epoxy-terminated silane is interposed between lid 14 ofthin profile battery 10 and substrate 22 over node location 25. Further,a curable adhesive composition or mass 32 comprising an epoxy-terminatedsilane is interposed between can 12 of thin-profile battery 10 and nodelocation 24 on substrate 22. The preferred curable adhesive compositioncomprises a two-part epoxy resin and hardener system, wherein thepreferred epoxy-terminated silane comprises a glycidoxy methoxy silane,such as a glycidoxyproplytrimethoxysilane, with3-glycidoxyproplytrimethoxysilane being a specific example. Theepoxy-terminated silane is preferably present in the curable adhesivecomposition at less than or equal to about 2% by weight, with less thanor equal to about 1% by weight being even more preferred.

One example 3-glycidoxyproplytrimethoxysilane is available from DowCorning Corporation of Midland, Mich., as Z-6040™ Silane. An exampleresin and hardener system for a conductive epoxy is available fromCreative Materials, Inc., of Tyngsboro, Mass., as Part Nos. CMI 116-37A™and CMIB-187™, respectively. In a preferred example, from 0.5 to 2.0weight parts of Z-6040™ silane is combined with 100 weight parts of theCMI 116-37A™ silver epoxy resin. A preferred concentration of theZ-6040™ is 1 weight part with 100 weight parts of epoxy resin. Such asolution is thoroughly mixed and combined with, for example, 3 weightparts of the CMIB-187™ hardener, with the resultant mixture beingfurther suitably mixed to form composition 26.

The composition is applied to one or both of battery 10 or substrate 22,and provided as shown in FIG. 3. An example size for conductive mass 26is a substantially circular dot having a diameter of about 0.080 inch(0.2032 cm) and a thickness of about 0.002 inch (0.00508 cm). Resistanceof a fully cured mass 26 was measured with an ohmmeter from the top ofthe mass to the substrate surface, which comprised a nickel-cladstainless steel Eveready CR2016™ button-type battery can. Typicalmeasured resistance where no epoxy-terminated silane or other additivewas utilized ranged from 10 ohms to 100 ohms, with in some instancesresistance being as high as 1000 ohms. These correspond to respectivecalculated contact resistances ranging from about 0.32 ohm-cm² to 3.24ohms-cm², with as high as 32.43 ohms-cm², when ignoring the volumeresistances of the epoxy mass and substrate. At the time of preparationof this document, 10 ohms (and its associated calculated contactresistance of 0.32 ohm-cm²) is considered high and unacceptable forpurposes and applications of the assignee, such as will be describedwith reference to FIG. 4. Yet where the epoxy-terminated silane wasadded, for example at a weight percent of 2% or less, the typicalresistance value and range dropped significantly to 0.1 ohm to 1.0 ohm,with 0.2 ohm being typical. These correspond to respective contactresistances of about 0.0032 ohm-cm², 0.032 ohm-cm², and 0.0064 ohm-cm².

It is perceived that the prior art conductive bonding without theepoxy-terminated silane results from poor wetting characteristics of theconductive epoxy with the metal outer surface of the button-typebattery, which typically comprises a nickel-clad stainless steel. Theepoxy-terminated silane significantly improves the wettingcharacteristics relative to the metal surfaces, such as nickel-cladstainless steel, in a conductive epoxy system in a manner which is notunderstood to have been reported or known in the prior art. Accordinglyin accordance with another aspect of the invention, a thin-profilebattery bonding method interposes epoxy between a battery and substratewith at least one of such having a metal surface to which the curableepoxy is to electrically connect. The epoxy has an effective metalsurface wetting concentration of silane to form a cured electricalinterconnection having a contact resistance through said metal surfaceof less than or equal to about 0.30 ohm-cm². More preferred, the epoxyhas an effective metal surface wetting concentration of silane to form acured electrical interconnection have a contact resistance through saidmetal surface of less than or equal to about 0.16 ohm-cm². Mostpreferred, such concentration provides a contact resistance of less thanor equal to about 0.032 ohm-cm².

The curable adhesive composition is then cured into an electricallyconductive bond which electrically interconnects the battery andsubstrate as shown in FIG. 3. In the preferred embodiment, suchelectrically conductive bond also is the sole physical support andconnection of the battery and its terminals relative to substrate 22.

Although the invention was reduced to practice utilizing formation of aconductive interconnection between a metal battery terminal and aprinted thick film on a substrate, the invention has applicability inmethods and constructions of producing an electric circuit comprisingother first and second electric components which electrically connectwith one another through a conductive adhesive mass comprising, in apreferred embodiment, an epoxy-terminated silane.

FIG. 3 depicts an exemplary battery powerable apparatus and electriccircuit 30 in accordance with an aspect of the invention. In onepreferred implementation, battery powerable apparatus 30 preferablycomprises a radio frequency communication device 50 as exemplified inFIG. 4. In such example, substrate 22 preferably comprises a flexiblecircuit substrate, with nodes 25 and 24 constituting a portion of aseries of conductive paths formed of printed thick film ink on surface23 of flexible substrate 22. Such conductive paths includes antennaportions 54. At least one, and preferably only one, integrated circuitchip 52 is mounted relative to substrate 22 and in electrical connectionwith a first portion of the substrate conductive paths. Mounting ispreferably with electrically conductive epoxy such as described above.Adhesive mass 26 electrically connects lid 14 of thin profile battery 10with a second portion of the substrate conductive paths. In thisexample, such second portion comprises a series of printed thick filmnodes 25. Conductive adhesive mass 32 electrically connects with a thirdportion of the substrate conductive paths, which in this examplecomprises node 24 in the shape of an arc.

An exemplary single integrated circuit chip is described in U.S. patentapplication Ser. No. 08/705,043, which names James O'Toole, John R.Tuttle, Mark E. Tuttle, Tyler Lowery, Kevin Devereaux, George Pax, BrianHiggins, Shu-Sun Yu, David Ovard, and Robert Rotzoll as inventors, whichwas filed on Aug. 29, 1996, and is assigned to the assignee of thispatent application. The entire assembly 50 preferably is encapsulated inand comprises an insulative epoxy encapsulant material.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1. A method of conductively interconnecting electronic componentscomprising: providing a curable adhesive composition comprising an epoxyterminated glycidoxy methoxy silane; providing first and secondelectronic components to be conductively connected with one another;interposing the curable adhesive composition between the first andsecond electronic components, wherein at least one of the componentscomprises a nickel containing metal surface over which the curableadhesive composition is received; curing the adhesive into anelectrically conductive bond electrically interconnecting the first andsecond components; and wherein the glycidoxy methoxy silane is presentin the curable adhesive composition at less than or equal to about 2% byweight.
 2. The method of claim 1 wherein the epoxy terminated silanecomprises a glycidoxyproplytrimethoxysilane.
 3. The method of claim 1wherein the epoxy terminated silane is present in the curable adhesivecomposition at less than or equal to about 1% by weight.
 4. The methodof claim 1 wherein the first electronic component comprises a firstconductive node and the second electronic component comprises a secondconductive node, wherein the first and second nodes comprise interfacesfor the electrically interconnecting the first and second components,and wherein the interposing provides the curable adhesive compositioninterposed between the interfaces.
 5. The method of claim 4 wherein thecurable adhesive composition contacts the interfaces.
 6. The method ofclaim 4 wherein the interfaces of the first and second nodes compriseopposing surface areas, and wherein an entirety of the curable adhesivecomposition is interposed within the respective opposing surface areas.7. The method of claim 1 wherein the curable adhesive compositioncomprises 0.5 to 2.0 weight parts of glycidoxy methoxy silane combinedwith 100 weight parts of silver epoxy resin.
 8. The method of claim 1,wherein the curable adhesive composition comprises 1 weight part ofglycidoxy methoxy silane combined with 100 weight parts of silver epoxyresin.
 9. The method of claim 1 wherein the nickel containing metalsurface comprises nickel clad stainless steel.
 10. The method of claim1, wherein the at least one component comprises a battery.
 11. Themethod of claim 1 wherein the at least one component comprises abutton-type battery.
 12. The method of claim 1 wherein the at least onecomponent comprises a thin-profile battery.
 13. The method of claim 1wherein the component other than the at least one component comprises aflexible circuit substrate.
 14. The method of claim 1 wherein theelectrically conductive bond comprises the sole physical support andconnection interconnecting the first and second components.
 15. A methodof conductively interconnecting electronic components comprising:interposing a curable epoxy composition between first and secondelectrically conductive components to be electrically interconnected, atleast one of the components comprising a battery having a metal surfacewith which the curable epoxy is to electrically connect; and curing theepoxy into an electrically conductive bond electrically interconnectingthe first and second components, the epoxy having an effective metalsurface wetting concentration of silane to form a cured electricalinterconnection having a contact resistance through said metal surfaceof less than or equal to about 0.3 ohm-cm².
 16. The method of claim 15wherein the epoxy has an effective metal surface wetting concentrationof silane to form a cured electrical interconnection having a resistancethrough said metal surface of less than or equal to about 0.16 ohm-cm².17. The method of claim 15 wherein the epoxy has an effective metalsurface wetting concentration of silane to form a cured electricalinterconnection having a resistance through said metal surface of lessthan or equal to about 0.032 ohm-cm².
 18. The method of claim 15 whereinthe metal surface wetting concentration of silane in the curableadhesive composition is less than or equal to about 2% by weight. 19.The method of claim 15 wherein the metal surface wetting concentrationof silane in the curable adhesive composition is less than or equal toabout 1% by weight.
 20. The method of claim 15 wherein the metal surfacecomprises nickel over which the curable adhesive composition isreceived.
 21. The method of claim 15 wherein the metal surface comprisesa first conductive node of the first electronic component and the secondelectronic component comprises a second conductive node, wherein thefirst and second nodes comprise interfaces for the electricallyinterconnecting the first and second components, and wherein theinterposing provides the curable epoxy composition interposed betweenthe interfaces.
 22. The method of claim 21 wherein the curable epoxycomposition contacts the metal surface and the second conductive node.23. The method of claim 21 wherein the curable epoxy compositioncomprises 0.5 to 2.0 weight parts of silane combined with 100 weightparts of silver epoxy resin.
 24. The method of claim 23 wherein thecurable epoxy composition comprises 1 weight part of silane.
 25. Themethod of claim 24 wherein the curable epoxy composition comprises 3weight parts of hardener.
 26. The method of claim 21 wherein theinterfaces of the first and second nodes comprise opposing surfaceareas, and wherein an entirety of the curable epoxy composition isinterposed within the respective opposing surface areas.
 27. The methodof claim 15 wherein the silane comprises epoxy terminated silane. 28.The method of claim 15 wherein the silane comprises glycidoxy methoxysilane.
 29. The method of claim 15 wherein the silane comprisesglycidoxyproplytrimethoxysilane.
 30. The method of claim 15 wherein themetal surfaces comprises nickel clad stainless steel over which thecurable adhesive composition is received.